The name Thrissur is a shortened form of Thiru-Shiva-Per-Ur (Tamil / Malayalam: തിരു-ശിവ-പേര്-ഊര്, Lord-Shiva-Name-Town) literally translates to 'The City or Town with the name of the "Lord Shiva"'. The name owes itself to the most prominent feature of the city, that is the Vadakkumnathan Temple, which has Shiva as its presiding deity.[25] Alternately, Thri-Shiva-Perur (Malayalam: ത്രി-ശിവ-പേരൂർ, Three-Shiva-Palace) means the place with three famous Shiva temples which are said to be – the Vadakkumnathan Temple, Kottapuram Shiva temple and the Poonkunnam Siva Temple.Thrissur was known by its anglicised name Trichur until 1990 when the Govt.decided to replace with its Malayalam name. Thrissur was also known as "Vrishabhadripuram" Kailasam of the South) in ancient days.[26]

[27] The Ramavarmapuram monument is in granite and is of the menhir type. The monument in Ramavarmapuram is 15 feet (4.6 m) in height and 12 feet 4 inches (3.76 m) wide. Since 1944, it has been protected by the Department of Archaeology. The monument is locally known as Padakkallu or Pulachikkallu. These menhirs are memorials put up at burial sites for the departed souls. They belong to the Megalithic Age of Kerala, which is roughly estimated between 1000BCE and 500CE.[28] All such monuments have not been dated exactly. Some experts are of the view that these are the remnants of the Neolithic Age in the development of human technology. The Ramavarmapurammenhir is also believed to be a monument belonging to the Sangam period in the South Indian history.[29]

Another monolithic monuments like Dolmens and rock-cut caves are at Porkulam, Chiramanengad, Eyyal, Kattakambal and Kakkad. According to historians, the dolmens are burial sites. Though most of the monuments were well protected, the dolmen at Porkulam was in a neglected condition. The monument excavated under eminent Archaeologist B. K. Thapar, between 1949 and 1950, was under the Department of Archaeology.[27] Another megalithic monument is situated at Ariyannur in Thrissur. This place has unravelled monuments such as the Kudakkallu or Thoppikkallu (Mushroom stones or Umbrella stones) and 'Munimada' (Saint's abode).[30] The laterite hillocks of Ariyannur rise to about 50 metres. Another reference in Ariyannur dates back to the early 15th century in the poem Chandrotsavam.[30]

The region can claim to have played a significant part in fostering the trade relations between Kerala and the outside world in the ancient and medieval period. The early political history of Thrissur is interlinked with that of the Chera Dynasty of the Sangam age, who ruled over vast portions of Kerala and Tamil Nadu. After the Cheras, the place was later ruled by the Kingdom of Cochin (Perumpadapu Swaroopam). Later, a powerful dynasty known as Zamorins of Calicut captured most of the Thrissur in 14th and 15th century.

Next was the turn of Portuguese who ruled Thrissur in the 16th century. In the beginning of the 17th century the Portuguese power was reduced and Dutch became the main power. With the help of Dutch, Cochin Royal Family recaptured Thrissur from Samoothiri in 1710.[31]

However, during 1750–60 Hyder Ali, the Sultan of Mysore, attacked Thrissur and became tributary of the Kingdom of Mysore. Tipu Sultan, his son led another invasion in 1786 to Thrissur, where he destroyed the churches of Syrian Malabar Nasrani community and Hindu temples. Tipu Sultan's Army set fire to the church at Palayoor and attacked the Ollur church.[32] The economy of Thrissur totally collapsed because of this invasion.[33] Later he made a retreat from Thrissur, which served as the headquarters of Kerala region, after the Srirangapattanam war. In the meantime, Rama Varma X, the successor of Sakthan Thampuran signed a treaty with East Indian Company, and made Cochin a subsidiary of the British.

The Indian freedom movement struggle also grew in momentum in Thrissur after a Committee was formed in 1919 of the Indian National Congress. In 1921, the Civil Disobedience Movement also attracted a large number of people into the freedom struggle. In 1927 Mahatma Gandhi visited Vivekodayam School in the city.[34] In 1934, father of the nation, again visited the city for the housewarming of Barrister Krishna Menon. The house afterwards was known "Gandhi Mandiram" in Chembukkavu.[35] In the mean time, R. K. Shanmukham Chetty, the controversial Diwan of Cochin Kingdom from 1935 to 1941, was developing City by constructing Thrissur Town Hall and Ramanilayam. Even now also two monuments remain as the epicentre of Kerala politics. DR M R Menon, a minister in Government of Kochi was instrumental in building the Municipal Corporation Building, Thrissur and the Municipal Office Road. He even concerted Swaraj Round and other peripheries of the city road.[36][37]

The Thrissur Kole Wetlands is one of largest, highly productive and threatened wetlands in Kerala. It acts as natural drainage for City of Thrissur.

The city of Thrissur is situated in Thrissur District of Central Kerala in India. The city is located at 10°31′N76°13′E﻿ / ﻿10.52°N 76.21°E﻿ / 10.52; 76.21 and has an average altitude of 2.83 metres. The city is 75 km north-east of Kochi, 133 km south-west of Coimbatore and 144 km south-east of Kozhikode.[41] The city is located in a hillock called Thekkinkadu Maidan which is the second highest point in city after the Vilangan Hills. From the hillock, the geography of the city move towards middle land where Thrissur Kole Wetlands is situated. The Kole Wetlands act as a natural drainage for the city where the water is carried out to river and from there to the Laccadive Sea, thus keeping Thrissur city safe from flood waters which affect most of the other cities in Kerala. [42][43][44][45] Different ponds, rivers and canals also keep the ground water safe from salt waters. The city is located in midland regions of Kerala, with an extended part of Palakkad plains.[46] The city geologically is composed of Archaean gneisses and crystalline schists. Major parts of city is covered by Archaeans rocks.[47] The city lies near the centre of the Indian tectonic plate (the Indian Plate) and is subject to comparatively little seismic or volcanic activity.

Under the Köppen climate classification, City of Thrissur features a Tropical monsoon climate. Since the region lies in the south western coastal state of Kerala, the climate is tropical, with only minor differences in temperatures between day and night, as well as over the year. Summer lasts from March to May, and is followed by the South-west monsoon from June to September. October and November form the post monsoon or retreating monsoon season. Winter from December through February is slightly cooler, and windy, due to winds from the Western Ghats.[48]

The City is drained in the monsoonal season by heavy showers. The average annual rainfall is 300 cm. The South-west monsoon generally sets in during the last week of May. After July the rainfall decreases. On an average, there are 124 rainy days in a year. The maximum average temperature of the City in the summer season is 33-degree Celsius while the minimum temperature recorded is 22.5 degrees Celsius. The winter season records a maximum average of 29-degree Celsius and a minimum average of 20-degree Celsius.[48]

Thrissur is home to many leading Malayali entrepreneurs,[18] and is a major financial and commercial hub of Kerala.[19] Historians say that King Sakthan Thampuran had invited several Syrian Christian families and Brahmins to settle in Thrissur city from their business centres in adjoining areas. Soon, Thrissur became a flourishing centre of internal trade in Kerala. Thrissur is one of the major manufacturing centres of plain gold and rolled gold jewellery in South India; up to 70% of Kerala's jewellery is manufactured in Thrissur. There are around 3,000 gold ornaments manufacturing units in the city and 40,000-odd artisans and others work in these units.[49][50] The industry provides direct and indirect employment to 200,000 people in Thrissur.[51][52] The artisans based in these units, craft nearly 85 percent of one tonne gold which is used per day in Kerala. About 90 tonnes of gold was being used annually in Kerala for manufacturing of ornaments daily.

Modern retailing is a big business and revenue earner for the city. Jewellery and textile retailing occupies a major part of the retailing business in Thrissur. The city is considered as hub of jewellery and textile business in Kerala. Most of the jewellery groups have outlets in Thrissur and provide jobs to thousands of people. Kalyan Group, Jos Alukka & Sons, Joyalukkas and Josco Group have their bases in city.[64]InfoPark Thrissur, the fourth technology park in Kerala after Thiruvananthapuram and Kochi and Kozhikode is situated in Thrissur District.[65][66][67] Tourism has also contributed heavily to the economy of Thrissur. Domestic tourists generally use the city as a hub to explore the highly promoted tourism industry of the state of Kerala. The city with its temples, old churches and its culture, is ranked first in the number of domestic tourists visiting Kerala.[21]

Thrissur city functioned as a municipality since 1921 under the Cochin Municipal Regulations.[68][69] In 1932, the new corporation building was constructed, and in 1972 new areas from other Panchayats were added to the municipality.[68] On 1 October 2000, the municipal town was upgraded to the level of a Municipal Corporation with the Panchayats of Ayyanthole, Koorkkenchery, Nadathara, Vilvattom (part), Ollur and Ollukkara. The Corporation comprises three legislative assemblies Thrissur, Ollur and Cherpu.[70] The city is administered by the Thrissur Municipal Corporation, headed by a mayor. The corporation is the second-largest city corporation in the state of Kerala in India. The city is the only local body in Kerala which directly controls power, water supply and solid waste management system in the city.

For administrative purposes, the city is divided into 52 wards, from which the members of the corporation council are elected for five years. The corporation has its headquarters in Thrissur city.[68][71] The Thrissur Urban Development Authority and Town and Country Planning Department (TCPD) are the agencies that prepare development plan for the city.[72][73][74][75]

The city is the headquarters of Thrissur City Police and Thrissur Rural Police. The Thrissur City Police is headed by a Police Commissioner, an Indian Police Service (IPS) officer. The city is divided into two sub divisions, Thrissur and Guruvayur. It also operates 14 police stations, including a woman police station and a traffic police station.[76][77][78]

As of 2011[update] India census, Thrissur city had a population of 315,957.[84] Males constitute 48.2% and females constitute 51.8% of the total population numbering 152,296 and 163,661 respectively.[84] The density of population is 3,130/km2. The sex ratio is 1,092/1,000 male. The total number of the households in the city is 66,827. The average family size in the city is 4.27 members. The city has a slum population equivalent to 0.30% of the total city population and 0.37% of the Kerala's slum population. The city has an average literacy rate of 95.5%: male literacy rate is 97% whereas female literacy rate is 94.6%.

Thrissur Municipal Corporation is spread over an area of 101.42 km2. The city alone accounts for 38% of the urban population in the Thrissur District. Thrissur Urban Development Authority area encompasses the municipal corporation area and adjoining panchayats. The total area under municipal corporation jurisdiction is 101.42 km2, and the area under the Panchayats is 18.83 km2 Together, these constitute an area covering 120.25 km2.

Hindus constitute the majority with 54.2% of the population and numbering 171,252.[84]Christians constitute 40% of the population with 126,443 members.[84]Muslims constitute 5.4% of the population with 17375 members.[84]

Known as the Cultural Capital of Kerala, the city enjoys a thriving cultural tradition dating back to centuries, and being the centre of Kerala's cultural activities. Thrissur Pooram also called as 'the pooram of all poorams' is celebrated in every year in the month of Medam (mid-April to mid-may) as per the malayalam calendar. It is the biggest of all poorams held in Kerala. The city plays host, for 36 hours from the wee hours of the pooram day, to one of the most largest collection of people and elephants.[92][93][94][95]Puli Kali also known as Kavakali is another festival, which attracts thousands of people to the city. It is performed by trained artists to entertain people on the occasion of Onam, an annual harvest festival, celebrated mainly in Kerala.[96][97] The most important festivals celebrated in the City include Christmas, Onam, Easter, Eid and Vishu. The City is widely acclaimed as the land of elephant lovers.[98][99]Aanayoottu (feeding of elephants), is the world largest elephant feeding ceremony held in Vadakkunnathan Temple in the City annually. The ceremony is conducted on the first day of the Malayalam month of Karkidakam.[100][101][102]

The cuisine of Thrissur is linked to its history, geography, demography and culture. Rice is the staple food. Achappam and Kuzhalappam are popular snacks. Vellayappam, a kind of rice hopper is another dish which is special to the city.

The city has an ancient tradition of Ayurvedic treatment. From the Ashtavaidya tradition, Oushadhi, Vaidyaratnam Oushadhasala, Sitaram Ayurvedic Pharmacy Ltd and SNA Oushadhasala is located in city of Thrissur,[63] All these firms have been instrumental in spreading the fame of Kerala Ayurvedic treatment, as thousands of overseas patients visit the Ayurvedic treatment facilities in and around Thrissur, every year. Vaidyaratnam runs a medical college and Chikitsalayam, with global standards. Sitaram have a 100 bedded eight storied super speciality hospital in the city of Thrissur, envisaged as the first of its kind Ayurveda super speciality hospital in the country.[63]